- ➊ Draw some dominoes along the grid lines into the diagram. A domino consists of two orthogonally adjacent cells.
- ➋ In each domino one of the two cells is marked by a square. In vertical oriented dominoes the square marks the lower half of the domino.
- ➌ Cells marked with circles do not belong to any domino. A number in a circle indicates how many cells marked by a square are orthogonally adjacent.
- ➍ All remaining cells are black. All black cells must form a a single orthogonally contiguous area.
- ➎ The black cells must not cover an area of 2x2 cells or larger and must form an orthogonally contiguous area.
- ➏ Each domino must be orthogonally adjacent to at least one black cell.